The present invention relates to fasteners for connecting belt or strap ends and particularly to an improved two-member releasable buckle comprised of two identical components, or members having parts which are identically shaped, which are engaged with one another to securely fasten strap or belt ends together under heavy loads.
There are numerous types of buckles and fasteners commonly available for securing the ends of two straps together. Such buckles are commonly made out of molded plastic and comprise a male and a female member, each attached to a length of strap, and engaged with one another to fasten the ends of the straps to one another. One of the most common types of these buckles is made by the Fastex Company of Des Plaines, Ill. The fastening and release mechanism of this type of buckle comprises at least one relatively resilient male portion biased outwardly transversely toward a side edge so as to enable it to snap into place with a hooking action in a female buckle portion. The resilience of the male portion allows it to remain engaged with the female portion even in the absence of any tension on the buckle. Release is generally accomplished by squeezing the sides of the buckle at apertured points along the edges of the buckle assembly where each male portion is exposed. This action forces the male portion inwardly against its bias to disengage its hook from the receiving portion of the female portion and allows the male portion to be withdrawn. A version of a similar buckle using such a resilient hook means is shown in Lovato, U.S. Pat. No. 4,569,106. Lovato shows a buckle assembly in which each buckle-half member is identical and comprises one male and one female portion of the fastening mechanism.
In buckles using the action of a resilient hook such as described above, the security of the fastening is dependent entirely on the ability of the male portion to withstand tension as well as the certainty of the hooking action of the male portion(s) into the female portion(s). Because of the need for flexibility of the male portion in such a buckle and the resultant limited thickness of that portion in order to provide such flexibility, the ability of the buckle to resist tensile forces applied to the fastened buckle is compromised in order to provide a more readily operable release mechanism. Similarly, since such buckles are intended to be releasable with a minimum amount of relative movement of the engaging portions both the male and female portions have small engaging surfaces and corresponding support structures, each of which comprises only a relatively small portion of the transverse cross sectional area of the buckle. Such buckles are designed more toward their ease of release than toward their security in fastening. In use, buckles of this resilient hook type are also subject to wear of the hooking portions of the male and female portions since such hooking portions tend to have a small contact area. This wear is amplified by the increased abrasive action resulting from normal dust and dirt present in outdoor environments where such buckles are commonly used. Even a moderate degree of wear of the engaging portions of such buckles eventually results in a failure of the buckle's ability to withstand any significant tension applied to the straps or belts which the buckle is used to connect. By virtue of their ease of release, such buckles are also subject to inadvertent release when under tension. This makes them less desirable for use where a high degree of security is desired when the buckle is used to resist a significant load and where a releasable fastening means is desired. Such applications may include, for example, use of buckles in freight securing means, safety belts, harness assemblies for rock climbers and parachutists, or any application where straps are used for lifting.